Multiplexed Cassegrain Reflector Antenna for Simultaneous Generation of Three Orbital Angular Momentum (OAM) Modes

Abstract

A multiplexed Cassegrain reflector antenna with a 2 × 2 open-ended rectangular waveguide (OERW) matrix feed and an orbital angular momentum (OAM) mode mux is proposed for the simultaneous generation of three OAM modes (l = 0, ±1). The OAM mode mux (OMM) was designed using sequential combinations of quadrature hybrids, crossovers, and phase shifters to multiplex and demultiplex three OAM modes at the same time. The 2 × 2 OERW matrix feed and the OMM were separately measured and their performances were verified according to proposed theories. A near-field antenna measurement for a multiplexed Cassegrain reflector antenna was conducted to obtain the far-field magnitude and phase patterns around polar elevation angle θ and azimuthal angle ϕ, thus confirming that our antenna can produce three OAM modes simultaneously. We also measured the communication link characteristics of two identical multiplexed antennas. The measurement results show that the channel isolation of three OAM modes is more than 12.7 [dB] and 17 [dB] for fixed and compensated receiver positions, respectively, indicating that the proposed antenna system can be used for independent communication links with the same frequency and polarisation.

Target scattering characteristics for OAM-based radar

“…(18) and (19), simulations are conducted to obtain the ORCS and RCS for the cylinder target, shown in Figure 10. In the simulation, the signal frequency is f = 10 GHz and the target size is set as (a r ,h) = (0. the peak values of ORCS is no longer in the angle θ = 90 • and the distance between two peaks increase as the topological charge l increases.…”

“…14,16 Moreover, many approaches have been applied to collimate and converge the OAM beams to enhance the radar operating distance, including biconvex lens, 17 intensity controlled masks, 18 and reflectors antennas. 19 a Author to whom correspondence should be addressed. Electronic mail: liukang1117@126.com.…”

Honeycombed metasurface plate for generation of X‐band orbital angular momentum beam

“…With the rapid development of the modern communication systems and people's requirement for faster information transmission speed, orbital angular momentum (OAM) with infinite mutually orthogonal modes theoretically has drawn great attention for its prospect of increasing communication capacity and spectral efficiency, which has been verified in mode multiplexing techniques of radio channels and millimeter‐wave communications . Many approaches such as aperture‐coupled uniform circular array antennas and multiplexed Cassegrain reflector antennas have been proposed for OAM generations. However, these antennas need complicated feed networks which are difficult to design.…”

Microwave Orbital Angular Momentum Mode Generation and Multiplexing Using a Waveguide Butler Matrix

“…Optical OAM modes can be used as micro-particle rotating tweezers [2] and for quantum key distribution [3], and their use in high-capacity data communications has been attempted [4]- [6]. The other approach is to generate all the multiplexed OAM modes simultaneously, using a Butler matrix and a uniform circular array (UCA) [11], [12]. The advantage of OAM modes when applied to communications lies in their spatial orthogonality, which allows sharing the same frequency band, time slot, polarization, and spatial channel with other OAM modes.…”

“…However, a single SPP or helical reflector can only generate one OAM mode, and the several different OAM modes should be optically multiplexed-with a beam splitter, for example [9]-before transmission or transmitted individually without multiplexing [10]. The other approach is to generate all the multiplexed OAM modes simultaneously, using a Butler matrix and a uniform circular array (UCA) [11], [12]. A UCA is an array of N sub-antennas located along a circumference at equal spacing.…”